Concerns around indoor air quality are growing among consumers and in the scientific/medical community. People are increasingly aware that indoor air pollution can be responsible both for short-term health effects such as eye irritation, headache, breathing problems, allergies, and for serious diseases like chronic respiratory syndromes.
There are numerous air cleaning devices on the market, most of them based on mechanical or electrostatic filters and/or negative ions production (ionizers). While they achieve a good removal of particulate air contaminants, they often fail to be effective on very small particles of the submicron range. Further, they are quite inefficient against bacteria and viruses, and especially vapor/gaseous contaminants like sulfur or nitrogen oxides, VOC's (Volatile Organic Compounds) and numerous species of radicals present in an indoor environment. In particular VOC's have a large impact on health and are responsible for odors, so that their removal is highly relevant to consumers. Lately, it has also been observed and reported that exposure to VOC's and other gaseous pollutants such as Nitrogen oxides can result in allergies or worsening of asthma conditions.
Further, while mechanical filters work in laboratory conditions, they soon get loaded with the filtered impurities and lose their effectiveness in real life conditions. Electrostatic filters, on the other hand, while suffering less from this drawback, present the problem that the charged surfaces must be effectively and frequently cleaned from the collected impurities while requiring special care to avoid re-emitting the impurities into the air. Filters impregnated with active materials that chemically interact with air contaminants are also available, but their limitation is similar to mechanical filters in that the impregnation gets soon exhausted or dries up, thus restricting the effective duration of the filter and requiring a frequent exchange.
DE-A-2 205 600 describes an indoor air cleaning apparatus wherein a slowly revolving drum is partially immersed in an aqueous agent solution and polluted air flows through the non-immersed portion of the drum. The kind and the nature of the agent to be used in this apparatus is not described at all, except that it is available in powder form and to be dissolved in water. In addition, that type of apparatus does not control the outlet air relative humidity, increasing the indoor air relative humidity during normal operation.
One of the problems one embodiment of the present invention addresses is to provide a stand alone and/or portable indoor air cleaning apparatus which is simple in construction and allows the efficient removal of dissolved or dispersed contaminants, in particular VOC's and other gaseous pollutants.